arXiv AI

LLM-Generated Feature Pools for Time Series Anomaly Detection

arXiv AI
Jun 29

When Is an LLM Worth It for Hyperparameter Optimization? A Budget-Matched Study on Tabular Data Finds the Warm-Start Is a Default Configuration, Not the Model

arXiv:2606. 21641v2 Announce Type: replace-cross Abstract: Large language models (LLMs) have been proposed as hyperparameter-optimization (HPO) advisors that "warm-start" search from prior knowledge, proposing strong configurations in very few evaluations.

By Carson Rodrigues, Oysturn Vas, Isaiah Abner DCosta, Nithish Kumar Prabhakaran
arXiv Machine Learning
Sep 16

Stream Assembly Is an Uncontrolled Treatment in Streaming Intrusion-Detection Benchmarks

The paper demonstrates that the way evaluation streams are assembled in streaming intrusion‑detection benchmarks—by interleaving, pooling, or replaying network captures—acts as an uncontrolled experimental variable that can significantly alter performance metrics. In the CICIDS2017 benchmark, reordering the same set of records under a fixed split changes the held‑out samples’ overlap, prevalence, and even reverses the ranking of two deterministic scorers. Similar effects are observed in the LITNET‑2020 benchmark, where pooling disjoint captures yields a single operating point that masks large variations in per‑capture prevalences, and minor changes in batch composition can shift reported AUC‑PR values by a few thousandths.

By Michel A. Youssef
arXiv AI
Sep 4

Witnesses Explain Anomalies

WAND is an unsupervised tabular anomaly detector that scores each point by how far its projection on unit‑sphere directions deviates from a sub‑Gaussian baseline. The directions that flag a point serve as its explanation, providing per‑feature attribution at no extra cost and recoverable via gradients. On 47 ADBench datasets, WAND matches or exceeds 16 baselines in ROC‑AUC while delivering more accurate, faithful explanations than post‑hoc SHAP, LIME, or ECOD, all with linear scoring time and a probe‑efficiency guarantee.

By Lamine Diop
arXiv Machine Learning
Aug 19

Training-Free Human-in-the-Loop Anomaly Detection via Memory Bank Correction

The paper introduces a training‑free, human‑in‑the‑loop anomaly detection framework that allows a domain expert to correct a PatchCore detector by editing its memory bank, without retraining or using gradients. Using only ten golden samples, operator corrections close a median 66% of the performance gap to a fully trained bank, improving 12 of 15 MVTec AD categories while harming none. The approach is evaluated with a rigorous held‑out protocol and shows that passive and active querying yield statistically indistinguishable gains, with a defect‑memory extension failing decisively.

By Ayusha Abbas, Saram Abbas, Kabita Adhikari